Answer:
20 Liters
Step-by-step explanation:
One way to look at it is that there are 1000 mL in one L. But I think a better way in general for unti conversions is to do it like this.
20000 ml * [tex]\frac{1L}{1000 mL}[/tex] Where you can just cancel out the units. Hopefully it made sense. If you were converting from L to ml you would use [tex]\frac{1000 mL}{1 L}[/tex]
